Many types of arrows are available for shooting with an archer's bow. An archer's choice of a particular arrow depends on the intended activity or use for the arrow. Arrows used for competitive target shooting generally differ from those used for hunting.
Arrows used for hunting typically comprise an arrow shaft and an arrowhead commonly referred to as a broadhead. A broadhead is mounted at a tip end of the arrow shaft opposite an arrow string engaging nock. Broadheads typically comprise a central ferrule which mounts a plurality of broadhead blade elements, each blade element presenting an inclined, razor sharp edge. These broadheads are designed for the purpose of striking and piercing a target, such as a game animal, and consequently inflicting a wound exhibiting profuse bleeding.
Broadhead blade elements typically resemble triangularly shaped razor blades. Two or more blade elements are typically mounted in longitudinally extending slots formed in the broadhead ferrule. These blades can be fixedly secured in the ferrule slots by several means. One means for fixedly securing blade elements in a broadhead is shown in
U.S. Pat. No. 4,986,550, to Segovia. Segovia shows a broadhead comprising an arrowhead body or ferrule with longitudinally extending, radially oriented slots for accepting corresponding blade elements. Each blade element includes a central flange from which a sharpened blade extends. The blade flanges have acutely shaped projections at opposing ends. As shown in FIG. 1 of Segovia one projection fits captively within a cooperating portion of the slot and the other projection is engaged by a cooperating washer, which, when compressed against the ferrule, fixedly secures the blade unit in the slot.
Another blade element securing means is shown in U.S. Pat. No. 4,210,330, to Kosbab. Kosbab shows, in FIG. 2 thereof, a modular broadhead having a central ferrule with blade engaging slots radially offset from the central axis of the ferrule in planes parallel to planes tangent to the peripheral surface of the ferrule. Each blade includes opposed acute angle projections that cooperate, at one end of the blade, with an annular groove formed in a tip that threadedly engages the ferrule and, at the opposed end of the blade, with a ferrule collar. The engagement of the tip and ferrule collar with the acute angle projections secures the blade in captive engagement with the ferrule.
It is also known in the prior art to attach blades in a broadhead by means of slots passing transversely or radially through a ferrule. The blades are pre-assembled as a rigid subassembly and then engaged with the ferrule. Thus, the broadhead blades are apparently replaceable only as a complete unit. This type of broadhead and securing means is shown in FIG. 1 of U.S. Pat. No. 4,558,868, to Musacchia. Still another means for securing blade elements is shown in U.S. Pat. No. 5,160,148, also to Musacchia. In this patent, there is shown in its FIG. 1, a broadhead having an elongated ferrule which receives and supports removable blade elements. The blade elements include a main portion and a mounting flange offset from the main portion by a fixed angular amount. The angular offset of the flange apparently corresponds to the angular disposition between any two adjacent radially oriented, longitudinally extending slots formed in the ferrule. When assembled, the flange of a first blade element and the main body portion of a second and adjacent blade element occupy each of the slots. Thus, the slots must be approximately twice the width of the blade element material therein.
Broadheads are often easily damaged during use. The blade elements, and particularly the razor sharp edge defined along portions of the blade element, are susceptible to damage due to missed shots or when the archer makes his shot but the broadhead strikes a large bone of a game animal. Where a shot is missed the broadhead may strike rocks or other hard objects that break the blade element or cause sever nicks in the blades' sharpened edges. Where the arrow hits its mark, the broadhead may hit a large bone causing the blade elements to break, usually when the broadhead hits the large bone obliquely and glances off the bone thereby imparting most of the impact energy along one blade element.
One consequence of broken blade elements is that the arrow cannot be used until the broadhead is repaired. This is so because a broadhead with broken and/or missing blade elements will become statically and aerodynamically unbalanced. This unbalanced condition will prevent a launched arrow from traveling an intended and predictable trajectory. Also, if the arrow with a damaged broadhead does hit its mark, the broadhead may not inflict the type or quality of wound that is humanely desired by bow hunters.
Where blade elements fracture upon impact with a game animal, the blade fragments may become lodged within the animal at locations distant from the point of impact or entry of the broadhead. Thus, the blade fragments become a hazardous foreign body in the animal. Since most of these animals are often processed into food, as meat, and into skins, these foreign bodies may constitute a hazard to the processor or consumer of the animal meat or skin.
Blade elements that are mounted into slots extending along a broadhead ferrule and secured fixedly only by engagement of acute blade projections at the opposed ends of the ferrule are particularly susceptible to separation of broken portions of the blade from the broadhead ferrule. When these types of blades fracture, the loss of only a portion of the blade element, initially, usually leads to the loss of the entire blade element because the blade element is not actually mechanically, captively engaged along its entire length by the ferrule and the mechanical engagement of the acute projections is breached when a portion of the blade element is lost.
Broadheads such as those shown in the Musacchia patents avoid this problem to a great degree since the blade elements are mechanically engaged with the ferrule along the length of the blade element adjacent the ferrule. This configuration causes problems in the practical use of the broadheads however. In the former Musacchia patent, the blade elements are mechanically interconnected to form a rigid subassembly which is only replaceable as a complete unit. Thus, even though only one blade element is broken the entire unit must be replaced. This is expensive and time consuming. Also, the ferrule for these broadheads is fabricated specifically for particular configurations of blade subassemblies. For example, a three blade subassembly will not adapt to a ferrule provided with four equally spaced ferrule slots; nor will a four blade subassembly fit a three slotted ferrule.
The latter Musacchia patent attempts to overcome the problems associated with requiring blade subassemblies by providing a broadhead with individual, replaceable blades. However, the broadhead of the latter Musacchia patent requires that a portion of the flange of one of the blade elements be positioned alongside the blade body of an adjacent blade element within the same slot. This configuration requires that the width of the slot be more than twice as thick as the blade width. A double width slot may result in a weaker ferrule because twice as much ferrule material is removed. Also, the number of blades capable of being supported by a broadhead of the latter Musacchia type, is limited because of the width of the slot necessary to mount the blade elements.
Therefore it may be seen that there is a need in the art for an archery broadhead having replaceable blade elements that are mechanically and captively engaged by the broadhead ferrule along substantially the entire length of a blade mounting flange and which maximizes the number of blade elements adapted to be supported by the broadhead ferrule.